Apparatus for the generation of electric high voltage impulses



p 0, 1935. T. E. ALLIBONE 2,014,219

APPARATUS FOR THE GENERATION OF ELECTRIC HIGH VOLTAGE IMPULSES Filed May 15, 1933 2 Sheets-Sheet 1 Fig.1.

Inventor Thomas E. Al I ibone,

His orney.

Sept. 10, 1935. T. E. ALLIBONE APPARATUS FOR THE GENERATION OF ELECTRIC HIGH VOLTAGE IMPULSES Filed May 15, 1933 2 Sheets-Sheet 2 h'wvemtor. Thomas EAlIibone. by DEL EUMZAA is Attorne g- Patented Sept. 10, 1935 UNITED STATES PATENT OFFICE APPARATUS FOR THE GENERATION OF ELECTRIC HIGH VOLTAGE IMPULSES New York ApplicationsMay 15, 1933, Serial No. 671,289

In Great Britain May 20, 1932 2 Claims.

This invention relates to apparatus for the generation of high voltage electric impulses. Such impulses are usually obtained from apparatus which includes a plurality of groups or stages 5 of condensers, high resistances and spark gaps, so arranged that the condensers can be charged up in parallel through the resistances until the spark gaps break down, whereupon series connections are established by the spark-gaps and lo the condensers discharge in series. Apparatus of this sort is commonly known as a Marx impulse generator or Marx type impulse generator.

In such impulse generators, ii the condensers n in number are each charged to a voltage V,

the output voltage is nV assuming that no energy is lost in heating the circuit. To obtain very high voltages, the input voltage or the number of condensers or both, can be iriade large, subject to the limitations that on the one hand it is diiflcult to construct condensers to withstand high voltages and on the other hand the losses increase with the number of stages and the spark gap losses are high. Furthermore, the overall size of the generator becomes inconvenient if air at ordinary pressure is the dielectric in which the condensers and spark gaps are mounted.

An object of the present invention is to provide apparatus for generating high voltage impulses which will not be subject to the disadvantages or limitations usually accompanying the ordinary Marx impulse generator. More specifically stated, the invention has for an object that of reducing the losses in generators of this type so that for a given output, the dimensions of such a generator may also be reduced. In carrying out these objects, in accordance with the present invention, the spark gaps are segregated from the other elements of the generator in a chamber or column in which air or other gas may be maintained at a comparatively high pressure. Under these conditions, the spacings of the gaps can be set or their spark-over voltages made greater than is the case when air or gas at atmospheric pressure is employed. In addition, the other elements of the apparatus or at least the condensers are provided with or are mounted in a dielectric of a strength greater than that of air, for example, a vacuum, oil,

bituminous material, oil impregnated paper, bakelite or even air under pressure. It will of course be understood that it is a relatively simple matter in practice to maintain the spark gaps which are usually enclosed in thick walled 5 tubes of insulating material, in air or gas at any desired pressure, even of many atmospheres, while the condensers may all be mounted in a tank filled with oil at atmospheric or other high pressure, or in an evacuated tank.

According to another feature of the invention 5 provision is made for varying as desired the pressure of the air or gas in which the spark gaps are immersed, whereby to vary smoothly and in a convenient manner the output voltage of the generator. Provision may also be made with 10 suitable and well-known means for varying the input voltage of the generator.

The tube containing the spark gaps may be mounted either inside or outside the tank containing the condensers, and in the latter case, i. e. when the spark gaps are outside of the tank, the leads from the condensers to the spark gaps are conducted from the condenser tank through suitable insulating bushings. The resistances which connect together the terminals oi the various condensers may also be located either inside or outside the condenser tank.

In some cases the high voltage terminals may be connected to a potentiometer in order that suitable fractions of the high voltage may be ob- 25 tained, and in such case the potentiometer may be located within the condenser tank. In order to damp out the oscillations which may occur in the wave front of the high voltage impulse a. suitable resistance may be located in the high 30 voltage generator in series with the spark gaps. Preferably this resistance is sub-divided into a number of portions which are included in the spark gap connections, as will be hereinafter de- 35 scribed.

In order that the nature of the invention may be more clearly understood, various methods of carrying out the same will now be described with reference to the accompanying drawings, in which 40 Fig. 1 is a diagrammatic representation of an exemplary installation, in sectional elevation, for carrying out the invention.

Fig. 2 is a similar view illustrating another embodiment; 45 Fig. 3 is a plan view of the apparatus shown in Fig. 2:

Fig. 4 is an electrical diagram showing a. resistance included in the high voltage circuit, and 50 Fig. 5 is an electrical diagram showing the modification wherein resistances are included in series in the leads to the spark gaps.

In all the drawings, the main condensers are indicated at Cl, C2 Cn respectively; the spark gaps are indicated at Fl, F2 Fn respectively,

and the resistances connecting the terminals of the condensers and spark gaps are indicated at WI. WV! Wn.

Referringnowtol'ig.1,Aisatankwhichmay be of metal, but is preferably of insulating materlal and is adapted to contain oil or other suitable fluid dielectric or a vacuum. Located withinthetankisatubeBofinsulatingmaterial, such as a phenolic condensation product, and is adapted to contain air under pressure. A pipe P with a suitable cock (not shown) is provided for admitting air into the tube B. Suitable means are also provided for supplying the dielectric to the tank. The condensers Cl, C! and the resistances WI, W2 are located within the tank and are connected as shown in the drawings to the spark gaps Fl, F2 which are suitably supported within the insulating tube 3. The condensers are arranged in a column one above the other and are conveniently formed of flat metal plates separated by insulating material. The spark gaps are preferably formed with spherical surfaces and are also located one above the other in the tube B.

Additional condensers, indicated at Cs, for stabilizing purposes are shown in the figure,

' shunting the spark gaps and also located within the tank A. The low potential leads D and E are shown as passing into the tank through suitable insulating bushings but the lead E, which is indicated as being-the negative or earth lead, need not of course, be insulated from the tank.

The high voltage lead is indicated at H and passesthrough thetankAbymea-nsofabushing adapted to withstand high voltage. The source of supply of low voltage to the terminals D and E is not shown but conveniently may be a rectifier connected to a source of alternating current. The resistances WI, W2 may consist of wire helically wound upon rods or tubes of insulating material. It will be understood, in accordance with the well known principles of the liars type impulse generators, that with the arrangement shown, if the voltage applied to the terminals D, E, is equal to V, the high voltage at the output terminals H, E will be substantially or nearly qual to nV where n is the number of condensers.

Referring now to Figs. 2 and 3, the structure ismbstantiallythesameasthatdescribedwith reference to Fig. l, but, as will be seen from Fig. 2, the insulating tube Bl containing the spark gaps I'l, I"! is located outside the tank A containing the condensers. This necessitates the leads from the condensers to the spark gaps passing through bushings in the tank wall as shown at f. In the arrangement shown in this figure the resistances WI, W2 are also located outside the tank and the stabilizing condensers are omitted. This ar- 5 rangement necessitates a large number of insulating bushings being provided in the tank wall for connections between the condensers, resistances and spark gaps. In some instances, however, this is not objectionable, for example connections to voltage points intermediate the high voltage terminals are necessary in the case where it is desired to supply a graded series of potentials to the electrodes of an electric discharge tube.

Referring now to Fig. 4, the diagram shows main condensers Cl, C! with spark gaps Fl, F2 and intermediate resistances WI, W2 Connectedin circuit with the high voltage terminal is a resistance r. The high voltage terminals are shown as being connected to a representative circuit composed of a sphere measuring gap M and an insulator I. The function of the resistance r is to damp out the oscillations which would otherwise arise on the front of the wave. The resistance r is preferably located within the tank containing the condensers.

In place 01' a single resistance the resistance 1 may be subdivided into a number of smaller resistances which are included in circuit with the spark gaps. For example, as shown in Fig. 5, each of the spark gapsFl, F2 has resistances rl, r1, rl, rl included in the leads so that a very compact arrangement is obtained. In this case the resistances should preferably be located within the oil tank containing the condensers. The same external circuit is shown in this figure as in Fig. 4, but it will be understood that the high voltage may be employed for any purpose for which it is required.

I claim:--

1. A high voltage impulse generator including condensers and spark gaps, said condensers adapted to be electrically charged in parallel and discharged in series through the spark gaps, said condensers mounted in an evacuated enclosure.

2. A high voltage impulse generator including condensers and spark gaps, said condensers adapted to be electrically charged in parallel and discharged in series through the spark gaps, said condensers mounted in an enclosure containing gas at a relatively high pressure and said spark gaps mounted in an enclosure containing a dielectric greater than that of air.

THOMAS EDWARD ALLIBONE. 

